Impulse coupling for magnetos



Sept. 24, 1935. w BORGERD 2,015,546

IMPULSE COUPLING FOR MAGNETOS Filed July 20, 1933 5 sheets sheet l Sept. 24, 1935 w. F. BORGERD 2,015,546

I IMPULSE COUPLING FOR MAGNETOS Filed July 20, 1933 3 Sheets-Sheet 2 Sm, wags. W F BORGERD ww m IMPULSE COUPLING FOR MAGNETOS Filed July 20, 1933 5 Sheets-Sheet 3 Patented Sept. 24, 1935 IMPULSE COUPLING FOR MAGNETOS William F. Berger-d, Chicago, Ill, assignor to Intor-national Harvester Company, a corporation of New Jersey Application July 20, 1933, Serial No. 631,324

15 Claims.

This invention relates to an impulse starter as utilized in connection with magnetos. Through the instrumentality of such mechanisms when the engine is turned over in the ordinary manner,

5 the magneto is operated with an accelerated rotation wlu'ch results in a good spark in the engine cylinder even at a very slow speed of rotation of the engine.

The principal object of the invention is an improvement in an impulse starter of the full automatic type, that is, one in which the accelerating means is thrown out of operation when the engine attains a certain speed and is automatically reset or thrown into operative position when the steps or slows down to a predetermined speed. This object and others which will be pointed out in the detailed description to follow are accomplished by a construction as shown in the accompanying drawings, in which;

Figure l an end elevation, showing a portion of a magneto housing and the end at which the impulse starter is mount-ed;

Figure 2 is an enlarged detailed view of the pawl disengaging latch which forms a part of the mechanism;

,ure 3 is an enlarged detail of the restraining pawl as utilized in the device;

Figure 4 is a section taken on the line 4-4 of Figure 1;

Figure 5 an enlarged detail view of the resetting pawl as utilized in the device;

Figure 6 is an enlarged perspective view of the engaging end of the re-setting pawl shown in Figure 5;

Figure 7 is an enlarged detail of the latch as used in the illustrated construction;

Figure 8 is a face view of one of the members constituting the accelerating means;

Figure 9 is a face view of the second member constituting the accelerating device. The pawl disengaging cams are shown in section in this view, in position against the stops formed on this member; and,

Figure 10 is a plan view of the members constituting the accelerating device, showing the stop means as formed on the two members.

Referring to Figure i, a portion of the casing IQ of a magneto of any conventional construction is shown. Said casing forms a support for the nonrotating parts of the embodiment of the invention illustrated, as will be hereinafter described. The parts of the impulse starter are in the main carried on the armature shaft l l, a portion of which is shown extending from the magneto casing 10. One member l2 of the accelerating means, which may be termed as the accelerating disk, is secured on the tapered end of the shaft II by a nut l3 threaded on the end of the shaft. The other principal member M of the accelerating means is provided with a sleeve-like extension I5, which rotatably fits over a sleeve-like extension iii of the member HE, A washer ll between the nut it and the end of the sleeve l5 forms a shoulder, thereby defining with the sleeve 5 and the radially extending portion of the member I2 retaining walls and a bearing surface for the sleeve portion l5 of the member I4.

As shown in Figures 7, 8, and 9, the member I4 is provided at diametrically spaced positions with axially extending stop portions l8. Said stop portions extend into circumferential openings I9 formed on the face of the circumferential porticn of the accelerating disk l2. As best shown in Figure 8, the stop I8 is formed at its rear side, speaking in terms of the direction of rotation which is indicated by an arrow on Figure 9, to abut a mating surface formed at the rear of the slot i9. The stops l8 are formed at their forward sides, that is, in the direction of rotation, with cam faces 28 for a purpose to be hereinafter described.

The member M on the face opposite the stop portions 18 is provided with diametrically spaced lugs 2 i Said lugs are constructed to fit into recesses 22 in a driving member 23. This is a conven'tional construction for transmitting power where a certain flexibility is desired to provide for misalignment of the driving and the driven shafts. The driving member 23 is secured to a member 24 which is rigidly mounted on a driving shaft 25. Said shaft may be driven in any conventional manner by suitable gearing connected to the crank shaft of the engine.

A housing 26 surrounding the parts making up the impulse starter is secured by cap screws 21 to the casing ill of the magneto. Said housing is cylindrical throughout the major portion, being provided with an outward extension at the top to provide means for supporting and encasing the non-rotating elements of the impulse starter jecting extension 32, which might be considered a notched end portion for purposes to be hereinafter described. The nose 3| is positioned to ride around the periphery of the accelerating disk I2, being held in contact therewith by the action of gravity on the pawl 31 which is of a substantial weight. Notches 33 are provided on the periphery of said accelerating diskp As illustrated, four of these notches are provided at equally spaced angular distances. The forward side of each of said notches, speaking in terms of the direction of rotation which is indicated by an arrow on Figure 1, is a long slant and the rear side is in the form of an abrupt wall, being substantially on a radius.

The member l4 of the accelerating means is provided at equally spaced angular distances with earns 34. It will be noted that the diameter of the outer portions of the cams is substantially the same as the diameter of the accelerating disk l2, the diameter of the cams being slightly less. This difference is overcome by a cut-away portion 35 on the accelerating disks adjacent the back edges or sides of the notches 33.

On a pin 36 extending into the casing l0 and into a boss 31 formed on the housing 26, a restraining latch 38 is pivotally mounted. Said latch has a long bearing portion on the pin and is provided with a stop 39 positioned to engage a stop 40 formed integral on the casing Ii). The restraining latch 38 is also provided with an upwardly extending latch arm 4! shaped at its outer end with a cam portion adapted to mate with a similar cam portion formed on the extension 32 of the restraining pawl 30. A pin 42 on said arm provides a means of attachment for a spring 43 which is secured at its other end to the casing I0. Said spring holds the stop 39 against the stop 40 on the casing.

The restraining latch 38 is also provided with a downwardly extending disengaging arm 44. Said arm extends at an angle toward the accelerating disk in the direction of rotation. It is curved at its bottom end to provide an engaging surface adapted. to contact with a disengaging pawl 45 pivotally mounted on a pin 46 mounted on the accelerating disk. The disengaging or re-setting pawl, as it may be termed, is of a peculiar construction. It is formed at one end with an axially extending end lug 45 extending out into a position such that in its path of movement the arm 44 of the restraining latch will be engaged. The other end of the pawl 45 is curved to fit around the armature shaft. It will be noted that the member is so constructed that its center of gravity will be at the curved end with respect to the pivot pin 46. A stop pin 48 is mounted on the accelerating disk I2, positioned to limit outward movement of the curved tail end of the pawl 45.

To provide means for holding the restraining pawl 30 out of engagement for inspection and repair, a pin 49 extends laterally toward the magneto side thereof. A lifting member 50, slidably mounted in a recess between the casing I0 and the housing 26, is provided with means for engaging the pin 49, whereby the restraining pawl may be lifted out of operative position and maintained in that position by manual means.

In the above description of the accelerating means the connection between the accelerating disk I2 and the other member 14 was not described, other than the stop means limiting relative movement of the members. A spiral spring 5! is provided at its inner end with a bent portion 52 adapted to fit into a notch 53 cut into the sleeve portion I5 of the member 14. The other end of the spring is provided with a coiled end 54 adapted to be fitted into a bore 54 formed in the peripheral portion of the accelerating disk l2. Said bore overlaps the inner edge, whereby the spring with its curved end may be fitted securely into position, as shown in Figure 8.

The operation of the impulse starter, as described, is entirely automatic in operation. Assuming that the engine is stationary and that it is to be cranked or started by manual means or other means, depending upon its own ignition for initial power, when the engine is turned over, the shaft 25, which is connected thereto, is put into rotation, power being transmitted thereby through the driving member 23 to the member [4 of the accelerating means, which may be termed the continuously rotating element of the accelerating means. The latch or restraining pawl 33, upon its preliminary rotation, engages one of the notches 33 on the accelerating disk l2. The spring 5! is thereupon compressed or wound into a position in which it has sufficient power, due to its inherent property, to rotate the magneto at a high rate of speed. As the rotation of the member it continues, one of the cams 34 engages the nose 3! of the restraining pawl 30, lifting it out of the latch 33 and out of restraining position, whereupon the accelerating disk is rapidly rotated by the action of the spring until the stop portion comes into contact with the back side of the stop H! on the member l4, as best illustrated in Figure 8. This action is continuous- 1y repeated during slow rotation of the engine.

Upon a predetermined speed of rotation of the engine and the continuously rotating member l4 of the accelerating means, the restraining pawl 39 is given a suflicient thrust about its axis to throw it past the arm 4| on the restraining latch 38, whereupon the restraining pawl is held out of engaging position with the notches 33. Following this action, the magneto is driven at uniform speed, the spring 5! being of suflicient strength to drive the magneto without relative movement of the two members of the accelerating means.

As the moving parts of the magneto approach the speed at which the restraining pawl is locked out of position, the re-setting pawl 45 is thrown out by centrifugal force with its heavy end out against the stop pin 48. In this position the lug 45 is brought inwardly toward the center of rotation of the accelerating disk 12, whereby it is in a position such that its path is free from the arm 44 on the latch 38. However, when the engine slows down to a predetermined speed, or is stopped, the re-setting pawl 45 drops back with its heavy end against the armature shaft, at each revolution of said shaft. This brings the lug 45 out into position where it strikes the arm 44, whereby the arm 4!, which looks the restraining pawl out of position, is lifted, allowing said pawl to drop back into operative restraining position. The entire cycle of operation, as above described, is then repeated.

The member 50 provides means for manually holding the restraining pawl out of position when such an operation is desired for inspection or repairing 0f the magneto.

It is to be understood that applicant has shown and described only a preferred embodiment of his improvement in automatic impulse starters and that he claims as his invention all modificaall) tion upon a predetermined angular movement of said pawl away from the accelerating member, and means carried by one of the rotating members operable to release said latch upon a predetermined minimum speed of rotation of one member of the accelerating means.

2. In a magneto having a frame structure and in combination ther with, an armature shaft, an accelerating member mounted on said shaft, a driving member therefor, resilient connecting means between said driving member and said accelerating member, stop means for said accelerating member including a pawl pivoted on the frame structure, means operated by the driving member for disconnecting said pawl, a latch mounted on the frame structure operative to engage and hold the pawl out of operative position upon a predetermined angular movement of said pawl away from the accelerating member, and means carried by one of the rotating members operable to release said latch upon a predetermined minimum speed of rotation of the accelerating member.

3. In a magneto and in combination, an armature shaft, a driving member therefor, resilient connecting means between said shaft and said member, a disk member carried by said armature, a pawl pivoted on the magneto, means formed on said disk to be engaged by said pawl forming thereby stop means for the armature shaft, means operated by the driving member for disconnecting the pawl from said disk, a latch pivoted on the magneto operative to engage the pawl when it is thrown from the armature disk a predetermined angular distance, and means operable upon a predetermined speed of rotation of the accelerating means for disengaging said latch, said means including a pawl mounted for rotation with the armature shaft.

4. In a magneto and in combination, an armature shaft, a driving member therefor, resilient connecting means between said shaft and said member, a disk member carried by said armature, a pawl pivoted on the magneto, means formed on said disk to be engaged by said pawl forming thereby stop means for the armature shaft, means operated by the driving member for disconnecting the pawl from said disk, a latch mounted on the magneto operative to engage the pawl when it is thrown from the armature disk a predetermined angular distance, and means for disengaging said latch, said means including a pawl mounted for rotation with the armature shaft.

5. In a magneto and in combination therewith, an armature shaft, a driving member therefor, a resilient driving connection between said shaft and said member, a stop means for said shaft including a pivoted pawl, means operated by the driving member for engaging thepawl and disconnecting the stop means from engagement, a latch extending toward the pawl, said latch having a portion adapted to engage with the pawl when the stop means is thrown out of engagement, and means carried by the armature shaft for disengaging said latch whereby the stop means is rendered operative.

6. In a magneto and in combination therewith, an armature shaft, a driving member therefor, a resilient driving connection between said shaft and said member, a stop means for said shaft including a pivoted pawl, means operated by the driving member for engaging the pawl and disconnecting the stop means from engagement, a latch oppositely pivoted with respect to the pawl and extending toward the pawl, said latch having a portion adapted to engage with the pawl when the stop means is thrown out of engagement, and means carried by the armature shaft for disengaging said latch whereby the stop means is rendered operative.

'7. In a magneto having a frame structure and in combination therewith, a rotatable armature shaft, a rotating driving member, accelerating means connecting said shaft and said driving member, a radially extending member carried by the armature shaft, stop means including a member mounted on the frame structure for iovement relative thereto, said means being operative to engage the radially extending member, means carried by the driving member effective to release said stop means, means mount- 0 ed on the frame structure for engaging said stop means and holding said means out of operative position upon a predetermined relative movement with respect to the frame structure, and

means carried by one of the rotating members operable upon a predetermined minimum speed of rotation of the accelerating means to release said stop means.

8. In a magneto having a frame structure and in combination therewith, a rotatable armature L shaft, a rotating driving member, accelerating means connecting said shaft and said driving member, a radially extending member carried by the armature shaft, stop means including a member mounted on the frame structure for movement relative thereto, said means being operative to engage the radially extending member, means carried by the driving member effective to release said stop means, a latch pivotally mounted on the frame structure for engaging said stop means and holding said means 0 out of operative position upon a predetermined relative movement with respect to the frame structure, and means carried by one of the rotating members operable upon a predetremined minimum speed of rotation of the accelerating means to release said latch.

9. In a magneto having a frame structure and in combination therewith, a rotatable armature shaft, a rotating driving member, accelerating means connecting said shaft and said driving member, a radially extending member carried by the armature shaft, stop means including a member mounted on the frame structure for movement relative thereto, said means being operative to engage the radially extending member, means carried by the driving member effective to release said stop means, means mounted on the frame structure for engaging said stop means and holding said means out of operative position upon a predetermined relative movement with respect to the frame structure, and a pawl pivotally mounted on one of the rotating members, said pawl being provided with means for engaging the means mounted on the frame structure for holding the stop means out of operative position and operative to release said means whereby the stop means is rendered effective.

10. In a. magneto having a frame structure and in combination therewith, an armature shaft, an accelerating diisk mounted thereon, a driving member, resilient connections between said member and said disk, notches formed around the periphery of said disk, a pawl pivoted on the frame structure and positioned to engage said notches, means actuated by the driving member operative to disengage the pawl, latch means mounted on the frame structure operative to engage the pawl upon a predetermined angular movement thereof and to hold said pawl out of engaging position with the accelerating disk, and means carried by the accelerating disk operative to disengage said latch means upon a predetermined minimum speed of rotation thereof.

11. In a magneto having a frame structure and in combination therewith, an armature shaft, an accelerating disk mounted thereon, a driving member, resilient connections between said member and said disk, notches formed around the periphery of said disk, a pawl pivoted on the frame structure and positioned to engage said notches, means actuated by the driving member operative to disengage the pawl, latch means mounted on the frame structure operative to engage the pawl upon a predetermined angular movement thereof and to hold said pawl out of engaging position with the accelerating disk, an engaging arm carried by said latch means and extending toward the armature shaft, a disengaging pawl pivotally mounted on the accelerating disk, said pawl being pivoted away from its center of gravity and mounted to be carried with the accelerating disk at or above a predetermined speed and to pivot with respect to said disk at or below a predetermined lower speed, said pawl being provided with means positioned to engage the disengaging arm on the latch means at said predetermined lower speeds.

12. In a device of the class described, the combination with the rotor of a magneto of a driving element for actuating the same, accelerating means associated with said rotor and connecting the same to said driving element, a pawl pivoted in close proximity to said accelerating means for restraining the rotor and actuating the accelerating means, a latch pivoted in proximity to said pawl and operable to engage the pawl and hold it in non-restraining position, and means carried by one of the rotating elements operative to release said latch.

13. In a. device of the class described, the combination with the rotor of a magneto of a driving element for actuating the same, accelerating means associated with said rotor and connecting the same to said driving element, a pawl 5 pivoted in close proximity to said accelerating means for restraining the rotor and actuating the accelerating means, a latch pivoted in proximity to said pawl and operable to engage the pawl and hold it in non-restraining position, and means carried by one of the rotating elements for releasing said latch when a certain angular velocity has been reached.

14. In a device of the class described, the combination with the rotor of a magneto and a driving element for actuating the same, of an accelerating disk associated with said rotor, means for affording a normal driving connection between said accelerating disk and said driving element and permitting relative movement there between under predetermined conditions, means for restraining movement of said accelerating disk, means for automatically throwing the restraining means into inoperative position, latch means operative to engage and hold said restraining means in non-engaging position, and means operable upon a predetermined low speed of one of the rotating elements for releasing said latch to permit the restraining means to drop into operative restraining position.

15. In a device of the class described, the combination with the rotor of a magneto and a driv ing disk for actuating the same of an accelerating disk associated with said rotor, said disk hav ing a notch with a shoulder at one end thereof, means for affording a normal driving connection between said accelerating disk and said driving element before permitting relative movement therebetween under predetermined conditions, a pawl pivoted in proximity to said accelerating disk, the ends of said pawl being provided with an inclined contact face adapted to engage the shoulder of said notch for holding the accelerating 'disk in restrained position, a latch pivoted in proximity to said pawl, means on the pawl to engage the latch when thrown a predetermined distance away from the accelerating disk, means for releasing said pawl from engagement with said shoulder to permit accelerated movement of the rotor and means carried with the rotating parts operable to engage and release the pawl latch at a predetermined angular velocity of the rotating parts.

WILLIAM F. BORGERD. 

